A Subscriber Identity Module or Subscriber Identification Module (SIM) card is a portable memory chip used mostly in cellular phones that operate on the Global System for Mobile Communications Network. A SIM card contains its unique serial number (ICCID), international mobile subscriber identity (IMSI), security authentication and ciphering information, temporary information related to the local network, a list of the services the user has access to and two passwords: a personal identification number (PIN) for ordinary use and a personal unblocking code (PUK) for PIN unlocking. 3GPP is now responsible for the further development of applications like SIM and USIM—the UMTS Subscriber Identity Module. The USIM brought security improvements like the mutual authentication and longer encryption keys and an improved address book. While 3G/LTE subscribers are allowed to access the 2G network, 2G subscribers cannot access the LTE network unless they replace SIM with USIM. In China, most of the China Mobile (CMCC) subscribers still hold 2G SIM card. While CMCC allow 3G/LTE subscribers use 2G SIM, USIM is a mandatory requirement for LTE UE. However, replacing all 2G SIM by USIM will take a long time.
The SIM replacement procedure today is inconvenient. A customer will likely to find the LTE mode on a newly bought 4G phone is unusable due to the 2G SIM. This may happen if the customer buys the LTE phone from other countries or from the open market, and many of the CMCC 3G users still use 2G SIM. The customer will then go to an operator store for SIM replacement, but access to the operator store may not always be convenient. The operator will then replace the SIM for the customer, including provide a new USIM card, activate the new USIM card and renew the contract, and associated the legacy phone number with the new USIM card. Due to the inconvenient SIM replacement procedure, the open market space for LTE smartphones becomes restricted. As a result, most users may directly buy LTE smartphones from the operators, and other medium or small smartphone vendors will have difficulty to survive due to the barrier to enter the operator purchase channel.
Therefore, the SIM to USIM replacement problem may become the bottleneck of LTE device market space. It degrades user's motivation to buy new LTE phone. The operator channel becomes more dominant. The problem will become more serious because LTE deployment gradually enters developing countries, which still have large amount of 2G users. A device-assisted solution for remote SIM replacement is sought.